Rubio was given the apparent suicide note in 1982, and was told Montgomery's son had understood her to have killed herself. Rubio sat on it for decades. In the biography she introduces the idea but is equivocating.
Just before the biography was published, however, Montgomery's granddaughter—who had not been shown the note—wrote a newspaper piece relaying what her father told her, that LMM killed herself.
Then Rubio's book disclosed the text of the note, which is overtly instructions on handling her journal, and so Rubio wishes it to not be a suicide note. I am not sure how that works, since the note seems to clearly have that implication, i.e. "It must end here…May God forgive me…my position is too awful to endure…"
https://lmmontgomeryliterarysociety.weebly.com/montgomerys-death-different-perspectives.html
